Is it better to hire a web designer or outsource the work?
Definitely hire and outside resource.
1- When you work with on outside firm, you save by not having to hire a person and have them on staff for this purpose. From your description of founders' expertise it sounds like you can maintain the site internally once its done and delivered.
2- By hiring an outside firm you also get the expertise and know how of hopefully a firm that has been doing this for living and for a while. They can offer you a range of solutions both in case of information architecture as well as design for the website. And the designs that you will receive is from a group of designers and not just one individual.
Hire a local firm or outsource?
End of the day it really depends on what you expect out of the first phase of your website. If you think using available templates out there or work of an outsource firm outside of US will satisfy you, then that would be the route to go. Be ready to deal with a little bit of back and forth and as mentioned in previous answers potentially some language barrier and all the good stuff that come along with working with firms outside of the country.
If you believe you want to have a website that you want to keep and grow with then I recommend working with a local firm that can sit with you face to face and understand your company, your product and market and can spend the time with you to evaluate your competition and then go to work and hopefully give you a solid solution that you can grow with and keep for a while. After all whatever perception and emotion your audience walks away with is going to be your brand. First impressions are very important.